In several respects, stringent requirements are placed on such plug-in connectors relative to the reliability of the connection that is produced and of the plugging-in process of a plug-in connector into its mating connector. In addition, the plug-in connection must be designed for a very long service life, during which fatigue phenomena of the seating of the plug must not occur.
A plug-in connector with a secondary locking mechanism is known from EP-1,207,591 A2, in which, during the plugging-in process of the connector into a corresponding mating connector and after the engaging of a primary locking mechanism, a secondary locking mechanism is moved into a slot between a tongue of the primary locking mechanism and the connector housing, in order to fill this slot and to prevent the primary locking mechanism from popping out of its locked position. In this case, the tongue of the secondary locking mechanism is continually under elastic strain in the final state, so that it may become subject to material fatigue, and, as the case may be, to material fracture over the long term. If pieces of the tongue of the secondary locking mechanism fall out of the slot, the secondary locking would therefore no longer be secure. At the very least, the correct seating of the plug-in connector in its mating connector would no longer be secure.
An electrical connector is known from DE 196 20,177 A1, in which an electrical contact between complementary connectors is first made toward the end of the plugging-in process in such a way that, during the plugging-in process, a spring is tensed, which moves the connectors into one another when a predetermined spring force has been exceeded and after release of its spring excursion.
DE 198 47,872 A1 describes an ignition bus housing with a secondary locking mechanism, which is pre-tensed by a spring during the plugging-in process and after engaging of the connector locking mechanism, moves by spring force over the connector lock and blocks it in its locking position.
In DE 100 05,858 A1, a spring clip acting as a safety device provides for the circumstance that the secondary locking can only take place when the connection of the connector has been concluded.
DE 100 35,726 A1 shows a contact support, in which a secondary locking mechanism is held back during the plugging-in process until the locking mechanism has been engaged. A spring tension is built up during the plugging-in process, and when this is released it moves the secondary locking mechanism into its final position. This release takes place after the spring tension has become large enough, due to the compression of the spring, in order to overcome an elastic resistance, which is formed by an elastic compressible clamp. The behavior of the latter determines the time point for triggering and this time can thus be determined only imprecisely and is hardly reproducible.
A plug-in connector with a secondary locking mechanism is known from EP 1,006,621 A1, wherein the secondary locking mechanism rests on one edge of the mating connector, until it is released by shifting laterally at a specific stage of the connecting process.